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	$137.76	10.497%	$152.2207	$152.22	$152.20	$152.20
Purchase #2	$199.25	13.585%	$226.3181	$226.32	$226.30	$226.30
Purchase #3	$82.82	8.155%	$89.574	$89.57	$89.55	$89.60
Purchase #4	$195.25	6.761%	$208.4509	$208.45	$208.45	$208.50
Purchase #5	$101.40	4.831%	$106.2986	$106.30	$106.30	$106.30
Purchase #6	$70.64	12.243%	$79.2885	$79.29	$79.30	$79.30
Purchase #7	$220.83	10.336%	$243.655	$243.66	$243.65	$243.70
7 purchase totals =	$1,007.95		$1,105.8058	$1,105.81	$1,105.75	$1,105.90