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	$197.80	6.462%	$210.5818	$210.58	$210.60	$210.60
Purchase #2	$241.53	7.433%	$259.4829	$259.48	$259.50	$259.50
Purchase #3	$177.68	7.755%	$191.4591	$191.46	$191.45	$191.50
Purchase #4	$76.73	10.860%	$85.0629	$85.06	$85.05	$85.10
Purchase #5	$201.75	10.515%	$222.964	$222.96	$222.95	$223.00
Purchase #6	$40.72	3.295%	$42.0617	$42.06	$42.05	$42.10
Purchase #7	$37.92	11.294%	$42.2027	$42.20	$42.20	$42.20
7 purchase totals =	$974.13		$1,053.8151	$1,053.80	$1,053.80	$1,054.00