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	$56.48	5.815%	$59.7643	$59.76	$59.75	$59.80
Purchase #2	$65.56	11.152%	$72.8713	$72.87	$72.85	$72.90
Purchase #3	$151.53	8.629%	$164.6055	$164.61	$164.60	$164.60
Purchase #4	$164.31	10.605%	$181.7351	$181.74	$181.75	$181.70
Purchase #5	$238.54	13.854%	$271.5873	$271.59	$271.60	$271.60
Purchase #6	$82.26	5.810%	$87.0393	$87.04	$87.05	$87.00
Purchase #7	$213.65	4.171%	$222.5613	$222.56	$222.55	$222.60
7 purchase totals =	$972.33		$1,060.1641	$1,060.17	$1,060.15	$1,060.20