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	$202.89	5.400%	$213.8461	$213.85	$213.85	$213.80
Purchase #2	$27.76	12.263%	$31.1642	$31.16	$31.15	$31.20
Purchase #3	$49.73	11.210%	$55.3047	$55.30	$55.30	$55.30
Purchase #4	$41.73	4.439%	$43.5824	$43.58	$43.60	$43.60
Purchase #5	$161.55	4.175%	$168.2947	$168.29	$168.30	$168.30
Purchase #6	$59.99	9.816%	$65.8786	$65.88	$65.90	$65.90
Purchase #7	$209.51	7.187%	$224.5675	$224.57	$224.55	$224.60
7 purchase totals =	$753.16		$802.6382	$802.63	$802.65	$802.70