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	$130.87	13.115%	$148.0336	$148.03	$148.05	$148.00
Purchase #2	$244.77	3.451%	$253.217	$253.22	$253.20	$253.20
Purchase #3	$36.31	11.774%	$40.5851	$40.59	$40.60	$40.60
Purchase #4	$195.29	6.797%	$208.5639	$208.56	$208.55	$208.60
Purchase #5	$100.44	13.379%	$113.8779	$113.88	$113.90	$113.90
Purchase #6	$225.77	7.809%	$243.4004	$243.40	$243.40	$243.40
Purchase #7	$89.44	7.639%	$96.2723	$96.27	$96.25	$96.30
7 purchase totals =	$1,022.89		$1,103.9502	$1,103.95	$1,103.95	$1,104.00