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	$192.77	10.242%	$212.5135	$212.51	$212.50	$212.50
Purchase #2	$90.73	9.642%	$99.4782	$99.48	$99.50	$99.50
Purchase #3	$58.91	4.597%	$61.6181	$61.62	$61.60	$61.60
Purchase #4	$149.33	13.520%	$169.5194	$169.52	$169.50	$169.50
Purchase #5	$234.79	4.369%	$245.048	$245.05	$245.05	$245.00
Purchase #6	$81.36	13.565%	$92.3965	$92.40	$92.40	$92.40
Purchase #7	$156.41	5.459%	$164.9484	$164.95	$164.95	$164.90
7 purchase totals =	$964.30		$1,045.5221	$1,045.53	$1,045.50	$1,045.40