Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$151.65	10.597%	$167.7204	$167.72	$167.70	$167.70
Purchase #2	$109.28	8.653%	$118.736	$118.74	$118.75	$118.70
Purchase #3	$202.69	9.813%	$222.58	$222.58	$222.60	$222.60
Purchase #4	$162.82	3.512%	$168.5382	$168.54	$168.55	$168.50
Purchase #5	$239.43	10.566%	$264.7282	$264.73	$264.75	$264.70
Purchase #6	$200.47	11.761%	$224.0473	$224.05	$224.05	$224.00
Purchase #7	$168.38	8.427%	$182.5694	$182.57	$182.55	$182.60
7 purchase totals =	$1,234.72		$1,348.9195	$1,348.93	$1,348.95	$1,348.80