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	$172.76	3.294%	$178.4507	$178.45	$178.45	$178.50
Purchase #2	$114.35	13.732%	$130.0525	$130.05	$130.05	$130.10
Purchase #3	$89.71	4.434%	$93.6877	$93.69	$93.70	$93.70
Purchase #4	$98.89	5.781%	$104.6068	$104.61	$104.60	$104.60
Purchase #5	$183.56	7.272%	$196.9085	$196.91	$196.90	$196.90
Purchase #6	$168.34	8.437%	$182.5428	$182.54	$182.55	$182.50
Purchase #7	$119.84	4.549%	$125.2915	$125.29	$125.30	$125.30
7 purchase totals =	$947.45		$1,011.5405	$1,011.54	$1,011.55	$1,011.60