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	$44.28	4.186%	$46.1336	$46.13	$46.15	$46.10
Purchase #2	$64.94	11.118%	$72.16	$72.16	$72.15	$72.20
Purchase #3	$76.39	7.426%	$82.0627	$82.06	$82.05	$82.10
Purchase #4	$54.71	13.843%	$62.2835	$62.28	$62.30	$62.30
Purchase #5	$92.76	4.282%	$96.732	$96.73	$96.75	$96.70
Purchase #6	$37.29	5.700%	$39.4155	$39.42	$39.40	$39.40
Purchase #7	$81.44	11.754%	$91.0125	$91.01	$91.00	$91.00
7 purchase totals =	$451.81		$489.7998	$489.79	$489.80	$489.80