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	$185.75	5.669%	$196.2802	$196.28	$196.30	$196.30
Purchase #2	$106.75	3.507%	$110.4937	$110.49	$110.50	$110.50
Purchase #3	$65.63	7.258%	$70.3934	$70.39	$70.40	$70.40
Purchase #4	$192.69	9.778%	$211.5312	$211.53	$211.55	$211.50
Purchase #5	$66.75	6.805%	$71.2923	$71.29	$71.30	$71.30
Purchase #6	$215.72	13.821%	$245.5347	$245.53	$245.55	$245.50
Purchase #7	$227.85	10.182%	$251.0497	$251.05	$251.05	$251.00
7 purchase totals =	$1,061.14		$1,156.5752	$1,156.56	$1,156.65	$1,156.50