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	$193.32	7.658%	$208.1244	$208.12	$208.10	$208.10
Purchase #2	$240.40	5.467%	$253.5427	$253.54	$253.55	$253.50
Purchase #3	$41.98	10.341%	$46.3212	$46.32	$46.30	$46.30
Purchase #4	$65.29	10.421%	$72.0939	$72.09	$72.10	$72.10
Purchase #5	$166.43	3.315%	$171.9472	$171.95	$171.95	$171.90
Purchase #6	$150.45	11.546%	$167.821	$167.82	$167.80	$167.80
Purchase #7	$179.74	13.765%	$204.4812	$204.48	$204.50	$204.50
7 purchase totals =	$1,037.61		$1,124.3316	$1,124.32	$1,124.30	$1,124.20