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	$200.25	11.102%	$222.4818	$222.48	$222.50	$222.50
Purchase #2	$221.34	9.824%	$243.0844	$243.08	$243.10	$243.10
Purchase #3	$91.43	5.140%	$96.1295	$96.13	$96.15	$96.10
Purchase #4	$184.38	13.417%	$209.1183	$209.12	$209.10	$209.10
Purchase #5	$189.71	7.787%	$204.4827	$204.48	$204.50	$204.50
Purchase #6	$190.58	5.111%	$200.3205	$200.32	$200.30	$200.30
Purchase #7	$243.93	6.817%	$260.5587	$260.56	$260.55	$260.60
7 purchase totals =	$1,321.62		$1,436.1759	$1,436.17	$1,436.20	$1,436.20