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	$85.30	12.113%	$95.6324	$95.63	$95.65	$95.60
Purchase #2	$95.29	11.481%	$106.2302	$106.23	$106.25	$106.20
Purchase #3	$32.38	3.392%	$33.4783	$33.48	$33.50	$33.50
Purchase #4	$170.88	8.550%	$185.4902	$185.49	$185.50	$185.50
Purchase #5	$246.60	11.486%	$274.9245	$274.92	$274.90	$274.90
Purchase #6	$201.83	10.223%	$222.4631	$222.46	$222.45	$222.50
Purchase #7	$240.95	9.224%	$263.1752	$263.18	$263.20	$263.20
7 purchase totals =	$1,073.23		$1,181.3939	$1,181.39	$1,181.45	$1,181.40