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	$197.82	3.873%	$205.4816	$205.48	$205.50	$205.50
Purchase #2	$186.79	9.501%	$204.5369	$204.54	$204.55	$204.50
Purchase #3	$225.82	9.663%	$247.641	$247.64	$247.65	$247.60
Purchase #4	$103.60	6.285%	$110.1113	$110.11	$110.10	$110.10
Purchase #5	$44.28	5.158%	$46.564	$46.56	$46.55	$46.60
Purchase #6	$141.71	7.729%	$152.6628	$152.66	$152.65	$152.70
Purchase #7	$72.48	13.679%	$82.3945	$82.39	$82.40	$82.40
7 purchase totals =	$972.50		$1,049.3921	$1,049.38	$1,049.40	$1,049.40