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	$130.82	9.123%	$142.7547	$142.75	$142.75	$142.80
Purchase #2	$5.93	6.527%	$6.3171	$6.32	$6.30	$6.30
Purchase #3	$135.76	11.675%	$151.61	$151.61	$151.60	$151.60
Purchase #4	$142.87	5.701%	$151.015	$151.02	$151.00	$151.00
Purchase #5	$23.53	3.871%	$24.4408	$24.44	$24.45	$24.40
Purchase #6	$39.78	13.671%	$45.2183	$45.22	$45.20	$45.20
Purchase #7	$170.79	8.814%	$185.8434	$185.84	$185.85	$185.80
7 purchase totals =	$649.48		$707.1993	$707.20	$707.15	$707.10